Take‐off angle dependent x‐ray photoelectron spectroscopy, secondary ion mass spectrometry, and scanning electron microscopy for determining the thickness and composition of passivation layers on technical aluminum foils

Angle dependent x‐ray photoelectron spectroscopy, static secondary ion mass spectrometry, and scanning electron microscopy have been used to investigate the effect of a cleaning procedure on the composition, morphology and thickness of passivation layers on technical aluminum foils. The results show that the cleaner, a solution of sodium carbonate, phosphate and surfactants, not only removes undesirable oil contaminations efficiently, but also etches the surface. Because magnesium‐rich inclusions are etched at a faster rate than the surrounding aluminum, the foil acquires roughness on the scale of about 100 nm, whereas at the same time the surface composition changes. In particular, small amounts of phosphate are deposited on the surface. All these factors are considered favorable for improved adhesion.